This Sunday at 9/8c, in the penultimate hour of Falling Skies Season 2, Tom, Anne, Weaver and the rest of the 2nd Mass arrive in Charleston, S.C. There, they have been told, hope lives on in the form of a small but reassembled U.S government. But what really awaits them?

For one, Tom (Noah Wyle) will come face to face with a former mentor, Arthur Manchester, played by Terry O’Quinn (Lost, Hawaii Five-0). In the end, though, will his be the face of a friend or unexpected foe?

“[Manchester] was a favorite history professor of Tom’s, which is kind of an odd coincidence…,” Falling Skies showrunner Remi Aubuchon tells TVLine. “But at the same time, it makes perfect sense. He’s done everything that Tom had hoped someone would do, which is try to recreate the United States out of the tatters that are left.”

“What’s always interesting about a Terry O’Quinn performance, in my opinion, is that there’s always something else going on inside there,” Aubuchon notes, “and that’s not too different from what’s happening with this character. He’s not exactly as he appears to be.”

O’Quinn debuts in this Sunday’s episode of the TNT drama, and returns for the season finale airing Aug. 19. Press PLAY below for an exclusive video sneak peek at the 2nd Mass’ introduction to the Southern comforts in Charleston.